Healthy kidneys remove waste and minerals from the blood. When kidneys fail, harmful waste builds up in the body, blood pressure may rise, and the body may retain excess fluid and not make enough red blood cells due to, for example, insufficient erythropoietin production. Hemodialysis is a common method for treating kidney failures and involves flowing blood through a filter to remove waste. Before hemodialysis can be done, a vascular access site must be formed that connects an artery to a vein and provides a way for dialysis tubes to access the artery and vein. The vascular access allows blood from the artery to travel through tubes into a filter of a dialysis machine that purifies the blood and then returns the purified blood back into the vein.
Currently, there are two main forms of permanent hemodialysis vascular access: native arteriovenous (AV) fistulas and synthetic AV grafts. An AV fistula is an induced native channel formed to connect an artery to a vein, whereas AV graft is an artificial channel that connects the artery to the vein. Both forms of vascular access sites often require a surgical procedure to generate openings in the vein and artery that eventually form the natural channel (i.e. anastomosis). After the openings are created, sutures or a clip are used to ligate the vein to the artery while the fistula matures. In contrast to AV fistulas, an AV graft is typically a synthetic looped tube that is surgically inserted to connect the opening of the artery with the opening of the vein.
Surgical vascular access creation typically involves inserting a catheter into the vein or artery to form openings between the vessels and requires precise execution for several reasons. First, a surgeon must approximate a location where the vein is in close proximity to the artery so that a connection can form between the two. In addition, current procedures also require a needle to deploy through the walls of both the vein and the artery. These factors combined can result one or more openings being created in either vessel that are unsuitable for fistula creation. For example, one may inadvertently create a hole in a vein at a location where the artery is too far away to form the vascular access site via anastomosis. In another example, if the needle is not properly positioned to deploy where the vein wall is positioned next to the arterial wall, one risks forming an wall opening in the vein at a location that cannot be aligned with the wall of the artery (e.g. opening of vein opposes wall of artery).